System for synchronizing a scanning electron beam with a rotating body



u liu-mt SLAHLH HMM R. L. PAIDOSH Aug. 20, 1968 SYSTEM FOR SYNCHRONIZING A SCANNING ELECTRON BEAM WITH A ROTATING BODY Filed Feb. 26, 1965 4 Sheets-Sheet l R. L.. SYSTEM FOR SYNCHRONIZING A SCANNING ELECTRON PAIDOSH Aug. 20, r1968 3,398,237.

BEAM WITH A ROTATING BODY 4 Sheets-Sheff:I

Filed Feb. 26, 1965 R. L. PAlDosH 3,398,237 SYSTEM FOR SYNCHRONIZING A SCANNING ELECTRON Aug. 2o, 196s BEAM WITH A ROTATING BODY 4 Sheets-Sheet 4 Filed Feb. 26, 1965 hNnwQ QS 28 w. nim SQ w SSS n bd. KNS S INVENTOR. Blf/CHA@ L ,DA/@05H United States Pte 3,398,237 SYSTEM FOR SYNCHRONIZING A SCANNING ELECTRON BEAM WITH A ROTATING BODY Richard L. Paidosh, Minneapolis, Minn., assignor to Minnesota Mining and Manufacturing Company,

St. Paul, Minn., a corporation of Delaware Filed Feb. 26,1965, Ser. No. 435,611

7 Claims. (Cl. 178-7.7)

This invention relates to a control system for an apparatus which engraves a rotating generally cross-sectionally circular shaped body having metallic peripheral surfaces by a high energy beam. In one aspect the present invention relates to an electronic synchronizing control system for synchronizing the operation of the energy beam with the rotation of the body to effect engraving of a particular spot on the peripheral surface of the body to a prescribed degree to produce on the body desired indicia or intelligence.

Previously, devices have been employed to effect engraving of nonrotating metallic surfaces by a high energy beam. In such devices, however, a high energy beam, such as an electron beam, had to be of sufficient energy to not only raise the temperature of a particular spot on the metallic surface to the melting point, but to vaporize the melted metal so as to effect removal thereof to engrave the metallic surface. These devices thus required very high energy beams and the beam had to be directed to a particular point on the metallic surface and had to remain focused on said point a sutliciently long time to vaporize the metal before that particular point of the metallic surface was engraved.

The known prior art systems have the disadvantages of requiring very high energy beams and extended operating time for the beam to melt and vaporize the metal to afford the engraving of each dot on a relatively large metallic surface. The control means for a beam in this known type of engraving device is relatively simple and are primarily cyclic timing means to control the intensity and position of the beam. However, since the beam intensity had to be so high and the time required is so great, these known devices did not produce satisfactory results.

An apparatus incorporating the system of the present invention uses a high energy beam but requires a lot less time to effect the engraving by utilizing centrifugal force to remove the molten surface particles formed by the beam rather than vaporization. It is difficult, however, in this apparatus to synchronize the scan sequence of the beam with the rotation of each selected spot on the drum to effect the desired engraving at each spot. The present invention provides an effective control for such apparatus and utilizes a novel combination of elements which synchroniz a scanning electron beam with a rotating cylinder such that the electron beam is directed to a particular spot on the peripheral surface of the drum through a predetermined range of rotational movement to afford the predetermined engraving. The electron beam scan -control is synchronized with the rotation of the cylinder so the electron beam strikes a particular spot on the periphery of the rotating cylinder throughout a predetermined arcuate movement. The scanning electron beam raises the temperature of the particular spot to the melting point whereupon the centrifugal force of the rotating cylinder removes the molten metal thereby engraving the surface at that particular spot.

The removal of the molten metal from the surface of the body by centrifugal force substantially reduces the engraving time for each spot.

The control means of this invention also includes means for directing the electron beam to effective programmed engraving of the entire metal surface of the rotating ICC cylinder, one spot after another in a predetermined pattern over said entire surface.

The above and further advantages of the present invention will become more fully apparent when considered in light of the following detailed description which refers to the accompanying drawings wherein:

FIGURES 1A, 1B and 1C are diagrammatic Views illustrating a sequence between the electron beam and the periphery of a rotating cylinder;

FIGURE 2 is a diagrammatic view of an apparatus utilizing an electron beam for engraving the metallic periphery of a rotating cylinder or plate Wound on a cylinder and having a synchronizing system in accordance with the present invention;

FIGURE 3 is a block diagram of the synchronizing systern of the present invention;

FIGURE 4 is a partial schematic diagram of the beam scanning synchronization control unit of FIGURE 3;

FIGURE 5 is a block diagram of an embodiment of a typical beam generator control programming means of FIGURE 3; and

FIGURE 6 is a partial schematic diagram of the ernbodiment described in FIGURE 5.

FIGURES lA, 1B, 4and 1C illustrate schematically the stages or position of the electron beam while engraving the metallic periphery of a rotating cylinder. In FIGURES lA to 1C the same elements are numbered with the same numbers for purposes of illustration.

In FIGURE 1A, a rotating cylinder 10 has a metallic periphery 12 which is to be engraved. For purposes of explanation, the periphery is to be engraved at ten particular spots denoted by the letters A to I. A beam generator 14 generates an electron beam 16. The beam 16 is focused and directed to scan as desired. The focusing and deecting is accomplished by suitable elements which are illustrated as la single coil 18 hereinafter referred to only as a deflecting coil. In FIGURE 1A, the bea'm focused to a point 20 is directed at point A on the metallic periphery 12 of the rotating cylinder 10 by the deflecting coil 18. This position of the electron beam is the starting position or quiescent scanning state of the electron beam 16 and the cylinder 10 is assumed to be rotating counterclockwise (ccw.) for purposes of explanation. As the periphery 12 is advanced ccw. by the rotating cylinder 10, point A will be moving ccw. at a velocity which is a function of the revolutions per minute (r.p.m.) of the rotating cylinder 10 and the radial distance of point A from the axis P of the cylinder. The detlecting coil 18 will deflect the electron beam such that beam point 20 will remain on a particular point A throughout a predetermined range of rotational movement. As illustrated the beam point 20 is directed `at point A throughout its movement from the position of FIGURE 1A to the position of FIGURE 1B.

When the beam reaches the end of its scanning sequence, as shown in FIGURE 1B the deflection coil 18 returns the electron beam 16 back to its quiescent position at a rate such -that beam point 20 is directed Substantially on point B. As illustrated in FIGURES 1A to 1C the cylinder is divided into 10 sectors for control purposes, and the beam is held on each spot on the cylinder as that spot is rot-ated through the arcuate displacement afforded by the cylinder rotating 36. In this time interval or less, depending on beam intensity, the metal of that particular spot will have been melted by the energy from the electron beam 16 to produce a 'maximum engraving. The r.p.m. of the rotating cylinder 10 is chosen so that the molten metal from spot A will be separated and removed from the periphery 12 by centrifugal force. If the beam is returned to its quiescent position before the cylinder -rotates through 36 a half tone or gray image may be formed.

From this diagrammatic illustration, it can be appreciated that the synchronizing means of this invention positions beam point on a particular spot of the metal periphery 12 and to synchronize the scanning rate of the electron beam 16 to the rotation of the cylinder 10 so as to engrave said particular point on the periphery thereof in accordance with a predetermined input affording the indicia to be produced on the cylinder at said particular s ot.

pReferring now to FIGURE 2 there is illustrated an apparatus, generally designated 62, and including a rotatable drum 22, having a metallic periphery 24, a motor 26 connected to a shaft 28 for rotating the drum 22, an electron beam generator 42, and beam focusing and deffecting means but only the deflection coils 48 and 50 are shown. An electrical control system 52 is provided for the apparatus 62 and includes a first and second signal generating means in the form of photosensitive devices 38 and 40, a scanning control synchronization unit S4, a vertical deflection control means 56, a coincident circuit beam generator control means 58, and a beam generator control programming means 60.

The electrical control system 52 is so associated with the apparatus 62 to synchr-onize the beam 44 with the rotating drum to impart thereto the desired programmed information. This system must therefore interconnect the cylinder and beam and programming means and accordingly includes a disc 30 rotatable with shaft 28 and positioned intermediate the drum 22 and the motor 26. The disc 30 `has a plurality of holes around its periphery. A plurality of circumferentially spaced 4holes 32 are disposed in the disc 30 near the peripheral edge thereof. iDisposed radially inwardly of the holes 32 is a single hole 34. Adjacent to the periphery of disc 30 and on one side thereof is a light source 36 and on the other side thereof are the two photosensitive devices 38 and 40. The photosensitive device 38 is positioned Ito receive light from source 36 which passes through the holes 32 and the photosensitive device 40 is positioned to receive light from source 36 which passes through the hole 34.

The photosensitive devices 38 and 40 are connected to the synchronizing uni-t 54 which is connected to and controls the deliecting and scanning coil and is connected to the vertical deflection control unit 56, which unit controls the vertical deflection coil 48. The vertical deflection coil 48 serves to deflect the electron beam 44 axially with respect to the drum 22 to move the point 46 of the beam progressively over the drum 22 in a predetermined sequence to make the apparatus engrave the drum through a plurality of axially adjacent tracks.

Additionally, the synchronization unit 54 is connected to the coincident circuit beam generator lcontrol 58. The beam generator control 58 is connected in turn to the beam generator 42 and actuates said generator 42.

The beam generator control programming means is connected to the synchronization unit 54 and to the beam generator control 58.

In operation, the motor 26 rotates the drum 22 and the disc 30 will permit light from the light source 36 to intermittently impinge on the photosensitive devices 38 and 40. The photosensitive devices 38 and 40 pass electrical signals to the scanning control synchronization unit 54. The synchroniaztion unit 54, via scanning coil 50, directs the beam point 46 of electron beam 44 on a particular point on the drum 22. The synchronization unit 54 signals coincident circuit beam generator control 58 to actuate the beam generator 42. The beam generator control programming means 60 signals the beam generator control 58 to again actuate the generator 42 to cut off the beam 44 or decrease its intensity after a predetermined scan sequence and concurrently signals the synchronization unit 54 to return the electron beam 44 to its quiescent position.

Each of the holes 32 as they pass the photosensitive device 38 send a signal to the synchronization unit 54 which controls the scanning coil 50 to engrave a plurality of points around the drum in a single track. After the entire track is engraved upon the completion of a predetermined number of revolutions, which are sensed by the photosensitive device 40, the synchronization unit 54 signals the vertical deflection control 56 to actuate the vertical deflection coil 48. The vertical deflection coil 48 then directs the following beam scanning sequences upon an adjacent track to thereupon engrave such adjacent track until the programmed information is completely imparted to the surface of the drum 22 in the forrn of an engravmg.

The above described embodiment is merely exemplary, and it is apparent that the vertical defiecion control 56 could actuate other devices other than a deflecting coil to move the beam axially along the drum from one track to another.

Referring now to FIGURE 3, the beam scanning synchronization unit 54 will be more fully described. The output of the photosensitive device 38 is supplied to a sector pulse shaper 64 which shapes and amplifies each pulse received from the photosensitive device 38.`A pulse is generated each time one of the pulse sector holes 32 passes the light source `36 to permit light to impinge on the photosensitive device 38. Generally, the output pulses from the photosensitive device 38 do not have a definite leading and trailing edge. Therefore, the sector pulse Shaper 65 sharpens the leading and trailing edges of each pulse to provide a useable pfulse output or signal.

Similarly, the photosensitive device 40 passes a pulse to a revolution pulse shaper 66 when the revolution pulse hole 34 permits light from the light source 36 to impinge on the photosensitive device 40. The function of the revolution pulse Shaper 66 is similar to the sector pulse Shaper 64, the only difference between the two vpulse shapers being the number of pulses received and shaped per revolution of the disc 30.

The output via line 68 from the sector pulse shaper 64 is supplied to a voltage ramp generator 70 which generates a ramp voltage in response to the sector pulses or signals received. The voltage ramp generator 70 applies a voltage ramp output via line 72 to a beam scanning control unit 74.

Concurrently, the revolution pulse Shaper 66 applies a revolution pulse via line 76 to a staircase generator 78. The staircase generator 78 receives the revolution pulses, and in response thereto generates an output voltage of a predetermined level via its output line 80. The staircase generator 78 has a second output line 82 which applies a bi-level signal to the vertical deflection `control 56 to indicate the completion of a stepping cycle of the staircase generator. The staircase generator 78 discretely and sharply raises the voltage level of its output pulse to a predetermined higher level in response to a revolution pulse received from the revolution pulse Shaper 66 via line 76. The staircase generator 78 has a plurality of discrete voltage levels or steps, and, for purposes of example, the staircase generator 78 could have, for example, 26 or 64 steps, the number of steps being equal to the number of spots engraved within a sector of a given track. When the staircase generator 78 reaches its maximum count, it will automatically reset itself Iback to its lowest level or step thereby ending its cycle. The output line 80 from generator 78 applies the discretelevels to the beam scanning control 74. The beam scanning control 74 performs the function of identifying a particular point on the periphery of the drum by the occurrence of a predetermined relationship between outputs of the staircase generator 78 and voltage ramp generator 70.

The beam scanning control 74 produces an output signal, when the predetermined relationship occurs and via line 84 directly controls a horizontal scanning control 86. The horizontal scanning control 86 is coupled via line 88 to a horizontal deflection amplifier 90. The horizontal deflection amplifier 90 is connected via line 92 to the scanning coil 50 of the apparatus 62.

The beam scanning control 74 simultaneously applies its output to the coincident circuit beam generator control 58 via coincident control line 94 which is connected to output 84. The operation of the coincident control line 94 will be described hereinafter.

Considering now the operation of the vertical deflection control 56, the vertical deection control 56 receives an output via .line 82 from the staircase generator 78 of the beam scanning synchronization unit 54. Output 82 applies a bi-level voltage from the staircase generator 78 to a second staircase generator 96. The staircase generator 96 is operatively connected to'the staircase generator 78 such that every time the staircase generator 78 reaches its maximum count and lreturns back to its lowest level or step to recount, the second staircase generator 96 increases or decreases from one discrete voltage level or step to a higher or lower discrete voltage level or step. The second staircase generator 96 may have, for example 2" steps or levels. The staircase generator 96 applies the staircase output voltage through its output line 98 to a vertical deflection amplifier 0 each time a signal is received from staircase generator 78. T-he vertical deflection amplifier 100 ser-ves the -function of amplifying the output of the second staircase generator 96 to deflect the electron beam in a vertical position `and in an amount proportional to the output voltage -received from said staircase generator 96. Each time the staircase generator 96 4rises from one discrete voltage level or step to a second discrete voltage level or step, the vertical deection control l56 detiects the electron beam in the vertical direction to an adjacent track, the number of steps in the staircase generator being representatives of the number of tracks on the drum to be engraved. Thus, between the operation of the vertical deflection control 56 and the 'horizontal scanning control 86, the electron beam position can be specifically controlled and the scanning rate thereof synchronized with the rotation of the drum.

The control of the intensity of the beam, that is whether the beam is on or olf, is determined by the coincid-nt circuit generator control 58. Coincident control .line 94 applies the output of the beam scanning control 74 to a ip-liop 102 such that the flip-op 102 is driven into a set condition. Prior to the flip-op 102 receiving an output from the beam scanning control, the flip-op is in the reset position. W-hen the flip-flop 102 is driven into the set condition, via coincident control line 94, an output via line 104 from the Hip-op 102 starts the beam intensity control 106. The beam intensity control 106, via line 108, sends a signal adapted to actuate the beam generator 42. The output from the flip-iiop 102 is also applied to a line 110, connected to .line 104, and transmitted to the beam generator control programming :means 60. This signal through the ip-op indicates to the programming means 60 that the flipflop 102 has been set, and that the electron beam is being generated and is scanning. The programming means 60 includes means to allow the electron beam t-o remain in the on position for Ia predetermined length of time or actuating interval whereupon the programming means 60 sends a stop signal back to the flip-iiop 102 via stop beam line 112. The lstop beam line 112 -resets the flip-iiop 102 thereby terminating the operation of the electron beam via control of the beam intensity control 106. Additionally, the stop beam line 112 is connected to the horizontal scanning control 86 by line 114 to signal the horizontal scanning control 86 to return the beam to its quiescent position.

Now tha-t the logical opera-tion of the synchronizing means has been discussed in reference to FIGURE 3, consideration will -now be given to FIGURE 4 which is a partial schematic diagram of the electrical operation of the beam scanning synchronization device 54 and illustrates the disc 30, one of the ten pulse sector holes 32 and the revolution pulse hole 34. The photosensitive devices 38 and 40 are disposed on one side of the disc 30 and the light source 36 is disposed on the other side of the disc 30, and as descri'bed previously the photosensitive device 38 will deliver ten sector pulses per revolution of disc 30 while photosensitive device 40 will deliver one pulse per revolution of disc 30, thus affording reference information concerning the position of at least one pre-chosen point on the periphery of the body to be engraved and information concerning the revolutions of the body.

Photosensitive device 38 is connected to the sector pulse shaper 64. The sector pulse Shaper 64 may be either a Schmidt trigger and an amplifier or a pulse generating circuit which generates a single pulse of uniform amplitude and duration in response to lreceiving a pulse from the pulse generating photosensitive device 38. The function of the sector pulse Shaper 64 is to have a pulse output wherein the pulse has a definite leading and trailing edge.

The sector pulse shaper 64 is connected to the voltage ramp generator 70.

Photosensitive device 40 is connected to the revolution pulse shaper 66, as above described, which produces a pulse output of uniform amplitude and duration in response to receiving a pulse from device 40. The revolution pulse sh'aper 66 may be any suitable device for obtaining this result such as a Schmidt trigger, an amplifier, or a pulse generating circuit. The output pulse of the revolution pulse sharper 66 is supplied to the staircase generator 78 and ultimately a staircase voltage output is applied to the beam scanning control 74, and specifically an emitter follower 150 thereof, as will be described below.

The electrical components of the voltage ramp generator 70 will now be described in detail together with a detailed description of the beam scanning control 74. Voltage ramp generator 70 has a flip-flop 116- having a set and reset condition and is normally in the reset condition. The iptlop 116 is connected to an NPN transistor 122 having a base 124, collector 126 and an emitter 128. The lower output of liip-op 116V is connected to an input resistor 134 at point 140. A capacitor 138 is connected in parallel with the input resistor 134 at points and 136. Also connected to point 136 is the base 124 of transistor 122 `and a source of negative potential 130 which is connected to one end of a resisto-r 132 with the other end thereof 'being connected at point 136.

The upper output 118 of flip-flopl 116 is connected through a resistor 142 and a point 144 to a collector 126 of t-he transistor 122. The emitter 128 of transistor 122 is connected to ground at 148. A capacitor 146 is connected in parallel circuit relationship with thecollector 126 and the emitter 18, -between point 144 andground 148.

The voltage ramp generator 70 is connected to the beam scanning control 74 by a line 72 from the point 144 of the generator 70 to an emitter 158 of ya unijunction transistor 152 in "said beam scanning control 74.

The beam scanning, control 74 basically comprises three transistors, the tinijunction transistor 152, an NPN transistor 154 and a PNP transistor 156. Unijunction transistor 152 has the em-itter 158, a first 'base 162 and a second base 160. The second base is connected to one end of a resistor 164. The other end of ressitor 164 is connected to the aforementioned emitter follower 150. The first base 162 of Unijunction transistor 152, is connected to one end of an inductor 166 at point 168. The other end of inductor 166 is connected to ground at 170. A resistor 172 is connected between the point 168 and 174 of the transistor 154. The transistor 154 has a collector 176 connected to one end of a load resistor 180 at point 188. The other end of load resistor 180 is connected to a positive potential source 182. An emitter 178 of transistor 154 is connected via line 184 to the ground at 170. The collector 176 of transistor 154 is connected to one end of a resistor 186 at point 188. Also connected to point 188 and in parallel with the resistor 186 is a capacitor 190, having their other ends connected in common at point 192. The transistor 156 has a base 194, a collector 196 and an emitter 198. The base 194 of transistor 156 is connected to the resistor 186 and capacitor 190 at point 192. The transistor 156 has a base 194, a collecsaid resistor 186 and capacitor 190 to said base 194. Base 194 is also connected to a negative potential source 204 through a resistor 200. This negative potential source 204 is also connected to one end of a collector resistor 206. The other end of collector resistor 206 is connected to the collector 196 of the transistor 156. The resistor 200 and the resistor 186 bias the operating potential of the transistor 156 to establish the operating point thereof. The emitter 198 of the transistor 156 is connected to the ground 170 by a line 208. The beam scanning control 74 is connected by a line 209, connected between the collector resistor 206 and the collector 196, and a line 210 to the flip-flop 116 of the voltage ramp generator 70 and by the line 209 and the line 84 to the horizontal scanning control 86.

In operation the voltage ramp generator 70 and staircase generator 78 concurrently apply their voltage outputs on the beam scanning control 74. Initially flip-Hop .116 is in the reset condition, the positive potential of lower output 120 is applied to the base 124 of transistor 122 via input resistor 1'34. Concurrently, the negative potential of voltage source 130 is applied to base 124 via resistor 132. The resultant voltage on base 124 is sufficiently positive to drive transistor 122 into conduction. When transistor 122 conducts, the collector 126 is connected to ground via the collector-emitter junction of transistor 122 thereby connecting the upper output 118 of flip-op 116 to ground 148 through transistor 122. Therefore the capacitor 146 which is connected to ground through the transistor 122 is completely discharged and the voltage ramp generator output line 72 is held at or near ground potential.

When the se'c'tor pulse shaper 64 receives a pulse from its photosensitive device 38, it transmits shaped pulses via line 68 to the flip-flop 116 causing it to change from the reset state to the set state. When ip-op 116 changes to the set condition, the upper output 118 changes from a ground potential to a positive potential and the lower output 120 changes from a positive potential to a ground potential. When the ground potential of lower output 120 of flip-flop 116 is applied to the base 124, transistor 122 is made nonconductive and the positive potential on upper output 118 of flip-flop 116 is applied across the resistor 142 and capacitor 146. The capacitor 146 accumulates a charge raising the potential on output line 72 toward the positive potential appearing on upper output 118. As is known, the capacitor charges at an exponential rate and the first 66% of the charging rate is substantially linear. This affords a desired characteristic such that the potential on output 118 is applied at the same linear rate on the point 144 and output line 72. This rising voltage applied to line 72 is thus applied to the emitter 158 of the unijunction transistor 152 in the beam scanning control 74.

The unijunction transistor 152 is concurrently receiving an input to the second base 160 from the staircase generator 78 via line 80, emitter follower 150 and resistor 164. Each time the revolution pulse Shaper 66 receives a pulse from the photosensitive device 40, the staircase generator 78 will discretely and sharply rise from one voltage level or step to a second definite voltage level or step. This voltage, each time it increases, is applied to the emitter follower 150 which isolates the output of staircase generator and applies the staircase voltage output waveform through resistor 164 to the second base 160.

At this time the second base 160 and the emitter 158 of the unijunction transistor 152 are receiving an increasing positive potential at a stepped rate and at a linear rate respectively. At a predetermined point, these potentials cause unijunction transistor 152 to break down and will exhibit its negative resistance characteristic at which time it conducts and the capacitor 146 discharges through the circuit including the emitter 158, the first base 162, inductor 166, ground 170, ground 148 and the capacitor 146. Thus the unijunction transistor 152 will conduct for a short period of time and will apply a positive potential to resistor 172 while it conducts. Upon the application of the positive potential to resistor 172, the base 174 of transistor 154 will become suiciently positive to drive transistor 1'54 into conduction. It is apparent that the unijunction transistor 152, during this operation essentially acts as a controlled oscillator having a variable time delay, the variable delay being determined by output voltages from both the voltage ramp generator 70 and the staircase generator 78. When transistor 154 conducts, collector 176 is essentially connected to ground 170 by emitter 178 and line 184. When collector 176 goes to ground, point 188 is also connected to ground and both remain at or near ground potential when the unijunction transistor 152 generates its single timed pulse output. The base 174 remains positive only as long as the unijunction transistor 152 is conducting to generate a pulse output and collector 176 will remain at ground potential for an equivalent length of time.

While collector 176 is connected to ground, point 188 is grounded, and this ground potential is also applied through the resistor 186-capacitor 190 parallel network to change the positive potential on base 194 of transistor 156, existing due to resistors 200 and 186 acting as voltage dividers, to a negative potential. The negative potential applied to base 194 of transistor 156 drives said transistor into conduction since the emitter 198 is held at a ground potential. When transistor 156 conducts, collector 196 will be connected to ground 170 through emitter 198 via line 208. The collector 196 of transistor 156 remains at ground potential only as long as its base 194 has a negative potential applied to it by resistors 186 and 200. It is apparent, that the output of transistor 154 is in the form of a pulse going from a positive potential to ground potential for a short duration and then back to a positive potential. The output of transistor 156 will be in the form of a pulse going from a negative potential to ground potential for a short duration and then back to a negative potential. The output of transistor 1'56 is fed through line 209 and line 210 back to the flip-op 116 of the voltage ramp generator 70 and through line 84 to the horizontal scanning control 86, and further through line 94 to the coincident circuit beam generator control 58. The output pulse of transistor 156 will reset the flip-Hop 116 and when so placed in the reset condition, transistor 122 is again made conductive thereby connecting capacitor 146 to ground to discharge it and to prepare the voltage ramp generator 70 for generating another voltage ramp output.

The voltage pulse applied on line 84 to the horizontal scanning control 86 will initiate the electron beam scanning sequence via said horizontal scanning control 86 which is connected to the horizontal deflection amplier via output 88. Horizontal deflection amplifier 90 will respond to the output of theV horizontal scanning control 86 to cause scanning coil 50 to move the beam through a predetermined scan sequence. Also, the voltage pulse applied to line 94 will simultaneously actuate the coincident circuit beam generator control 58 to actuate the beam generator 42.

From the above it will be noted that the beam scanning control 74 operates basically as -a controlled oscillator having a time delay circuit dependent on the voltages applied thereto by the voltage ramp generator 70 and the staircase generator 78. The time delay is obtained by varying the input voltage from the voltage ramp generator 70 and the voltage steps of the staircase -generator 78. The horizontal scanning control 86, upon receiving the pulse from the beam scanning control 74 has an electrical signal output to actuate the horizontal deflection amplier 90 which in turn has an output of varying level which corresponds to the signal received. The output of the horizontal deflection amplifier then controls the scanning coil 50 for moving the beam through a predetermined scan sequence. The scan sequence is thus initiated by the pulse to the horin zontal scanning control 86 and the same pulse indicates, through the coincident beam -generator control 58, to the beam generator control programming means `60 that the scanning sequence has been initiated and that the beam generator 42 is actuated. The beam programming means 60 controls the actuating interval of the beam scanning sequence which means that it will actuate the horizontal scanning control 486 to stop the scanning sequence and return the beam to its quiescent position.

Referring now to FIGURE there is illustrated one embodiment of a beam generator control programming means 60. The beam generator control programming vmeans 60 is adapted to receive desired information from a source, for example, punched paper tape, magnetic tape, or video tape, and this may be accomplished by suitable transducing means which converts the information to useable sign-als. As illustrated this transducing means is a photomultiplier 210. The output of the photo multiplier 210 is a signal, pulses, which are received by an amplifier 212 and amplified. The amplified signals are received by an emitter follower 214, which isolates the impedance of the amplifier 212 from the remainder of the circuitry. The output of the emitter follower 214 is applied to a sample and hold circuit 216. The sample and hold circuit 216 continuously samples the input information it receives until a signal is received from the coincident circuit beam generator control 58 by the start beam line 110. When a start signal is received the information which has been sampled and held is passed to a variable time width circuit 218 which will be described in greater detail as this description proceeds. The variable time width circuit 218 d-etermines, from the information received, how long the beam generator 42 should remain energized. The variable time width circuit 218, at the appropriate time passes a signal to a pulse out circuit 220. The pulse out circuit 220 applies a signal by the stop beam line 112 to the beam generator control 58 and to the horizontal scanning control 86 of the beam scanning synchronization unit 54 as described previously herein.

FIGURE 6 illustrates the beam generator control programming means 60 in greater detail. The photo multiplier 210 and the amplifier j 212 comprise any suitable apparatus and circuits for performing the results desired. The emitter follower 214 is fillustrated as comprising a single stage NPN transistor 222, a variable resistor 224 and suitable resistors which establish the operating point of the transistor 222. The variable resistor 224 is connected between the emitter of transistor 222 and ground. The variable resistor 224 is essentially a gain adjustment for adjusting the output or gain (amplification) of transistor 222 applied to the sample and hold circuit 216.

The signal from the emitter follower 214 is received in the sample and hold circuit 216 and is stored basically by a capacitor 226. The output signal from the emitter follower 214 is received by a field effect transistor 228 having a source 232, a drain 234, and a gate 236. The source 232 of field effect transistor 228 is connected to the variable resistor 224 of the emitter follower 214. The drain 234 of field effect transistor 228 is connected to one side of capacitor 226 at point 238. The other side of capacitor 22'6 is connected to ground 240. A second field effect transistor 230 having a drain 242, a source 244 and a gate 246 is also connected to point 238 by gate 246. The drain 242 of field effect transistor 230 is connected to a source of negative potential denoted generally as 248. The source 244 of field effect transistor 230 is connected to one side of a resistor 250 at point 252. The other end of resistor 250 is connected to a positive potential source 254. Point 252 is the junction for the output line 255 of the sample and hold circuit 216. An NPN transistor 256 having a base 258, a collector 260 and an emitter 262 is connected via a diode 264 to the gate 236 of the field effect transistor 228 and is connected to one side of a collector resistor 266 which is connected to a positive potential ysource 268. The emitter 262 of transistor 256 is connected to a ground 270. The base 258 of transistor 256 is connected to one side of a resistor 272, the other side of which is connected to a negative potential source 274. A base input resistor 276 is connected at a common point with the base 258 and resistor 272 and is connected in parallel circuit relationship with a capacitor 278. The input to the base input resistor 27-6`comes from the Aflip-flop 102 of the coincident circuit beam generator control 58 via line 110. The fiip-fiop 102 is normally in the reset position, and when in said position, the start beam line has a positive potential applied thereto from flip-flop 102. The positive potential from the line 110 is applied across base input resistor 276 to the base 258 of transistor 256 thereby driving the transistor 256 into conduction. Now, when the field effect transistor 228 receives signals from the emitter follower 214 said transistor 228 permits the signal to pass to and change the charge level of capacitor 226. When the iiipfiop 102 is set by a signal from the beam scanning control 74, line 110 is at ground potential and base 258 is subsequently driven sufficiently negative to return transistor.256 to a nonconducting state.

With transistor 256 in the nonconductive state, the collector 260 thereof is at :a positive potential, which will cause field effect transistor 228, through diode 264, to go to the nonconducting state. The impedance established ybetween the drain 234 and the source 232 of this field effect transistor 228 will now be in the high megohm range which normally is something in the order of to 300 ohms. With transistor 256 still in a nonconducting state, the charge level that had been placed into capacitor 226 from the emitter followe-r circuit 214 is retained by the capacitor due to the high impedance characteristics of the field effect transistors 228 and 230 connected as shown and described. The field effect transistor 230 is utilized primarily -as an impedance matching device between 'the capacitor 226 and the output point 252 of the sample and hold circuit 216 and isolates the capacitor 226 and reduces charge leakage therefrom to a minimum. The voltage applied to the line 255 of field effect transistor 230 is also applied to the variable tim'width circuit 218. When the field effect transistor 228 has a low impedance between the drain 234 and the source 232, due to transistor 256 being driven into conduction, the capacitor 226 adjusts its charge level to that voltage output of the emitter follower 214. I

The variable time width circuit 218 employs a first emitter follower 261, las al means of matching the i-mpedance between the output of the sample and hold circuit 216 and the |remainder of the circuitry in the variable time Width -circuit 218, which circuitry includes a unijunction transistor 262, a second emitter |follower 268, ramp generator 266, and an NPN transistor 274.

The output of emitter follower 261 is connected to the unijunction transistor 262, through its emitter 264, and a second Ibase of said transistor 262 is connected to output the second emitter follower 268. A first base 272 of the unijunction transistor 262 is connected to the transistor 274 to amplify the -pulse produced by the unijunction transistor 262 when it conducts. The unijunction transistor 262 conducts to produce a pulse -when a predeter mined relationship exists between the signals received from the sample and hold circuit 216 and the ramp generator 266. The ramp generator 266 is activated when the flip-fiop 102 is in the set condition. At the start, the Voltage level of the ramp generator 266 is at a positive poten'- tial and the output is a descending Iramp voltage signal. When the transistor amplifier 274 amplifies the pulse generated by the unijunction transistor 262, the output of transistor 274 is applied to a pulse out inverter 220 which resets the p-flop 102 and signals the beam scanning synchronization unit 54 to return the electron beam to its quiescent position.

Thus as signals from photo multiplier 210 are amplified by amplifier 212 and applied to the sample and hold circuit 216, the signal is retained as a charge on capacitor 226. When flip-flop 102 is set by the beam scanning control 74, transistor 256 becomes nonconductive and the charge level on capacitor 226 is isolated and reflected on output line 255. This output voltage is applied to the emitter 264 of unijunction transistor 262 and concurrently, ramp generator 266 applies a descending ramp output voltage to the second base 27,0 of said transistor 262, such that when these voltages reach a predetermined relationship the unijunction transistor 262 will conduct generating a pulse output which is am-plified and ultimately, through pulse out inverter 220, resets flip-flop 102 and actuates the horizontal scanning control to stop the beam scanning sequence.

Having thus described a preferred embodiment of the present invention, it is to be understood that various modifications will be apparent to one having ordinary skill in the art, and all such changes are contemplated as may come `within the scope of the appended claims.

What is claimed is:

1. An electrical control system for synchronizing the scanning movements of a high energy beam on the peripheral surfaces of a rotating body so that said beam mpinges on a particular point of said body during a predetermined arcuate displacement of said body, said body having reference means associated therewith for providing reference information concerning the position of at least one prechosen point located on peripheral surfaces of a said body, said system comprising (a) a first signal generating means for producing signals in response to such reference information indicating revolutions of a said body;

(b) a second signal generating means for producing signs in response to such reference information indicating arcuate displacement of said one point during each revolution;

(c) beam scanning control means vfor detecting when a predetermined relationship occurs between the output of said first signal gene-rating Imeans and the output of sai-d second signal generating means and for producing an output signal therefrom -when a sai-d predetermined relationship occurs;

(d) means interconnecting each of said first signal generating means and said second signal generating means with said bea-m scanning control means;

(e) beam -generator control means responsive to said beam scanning control means for producing an electrical signal output adapted to actuate a beam source;

(f) bealm ydeflecting control means responsive to said beam scanning control means for moving a said beam through a pre-determinedscan sequence', and

(g) beam programming means responsive to said beam scanning control Imeans for controlling the actuating interval of said beam generator control means and for actuating said beam defiecting control means to return a said beam to a starting position.

2. An electrical control system for synchronizing the scanning movements of a high energy beam on the peripheral surfaces of a rotating body so that said beam impinges on a particular -point of said body during a predetermined arcuate displacement of said body, said system comprising:

(a) reference means associated with a said body for providing reference information concerning the position of at least one prechosen point located on peripheral surfaces of a said body;

(b) a first signal generating means for producing signals in response to such reference information indicating revolutions of a sai-d body;

(c) a second signal generating means for producing signals in response to such reference information indicating arcuate displacement of said one point during each revolution;

(d) beam scanning control means for detecting when 12 a predetermined relationship occurs between the output of said first signal generating means and the output of said second signal generating means and for producing an output signal therefrom when a said predetermined relationship occurs;

(e) means interconnecting each of said first signal generating means and said second signal generating means with said beam scanning control means to transpose outputs from both of said signal generating means into signals useful for said beam scanning control operation;

(f) beam generator `control means responsive to said beam scanning control means for producing an electrical signal output adapted to actuate a beam soulrce;

(g) beam detlecting control `means responsive to said :beam scanning control means for moving a said beam through a predetermined scan sequence; and

(h) beam programming means responsive to said beam scanning control means for controlling the actuating interval of said 4beam generator control means and for actuating said beam defiecting control means to return a said beam to a starting position.

3. An electrical control system for synchronizing the scanning movements of a high energy `beam on the peripheral surfaces of a rotating body so that said beam impinges on a particular point of said `body during a predetermined arcuate displacement of said body, said body having reference means associated therewith for providing reference information concerning the position of at least one prechosen point located on peripheral surfaces of a said body, said system comprising (a) a first signal generating means for producing signals in response to such reference information indicating revolutions of a said body;

(b) a second signal generating means for producing signals in response to such reference information indicating arcuate displacement of said one point during each revolution;

(c) a staircase generator for generating a staircase voltage output in response to the output of the first signal generating means;

(d) a voltage ramp generator for generating a ramp voltage output in response to the output of the second signal generating means;

(e) first means interconnecting said first signal generating means with said staircase generator;

(f) second means interconnecting said second signal generating .means with said voltage ramp generator;

(g) beam scanning control means for detecting when a predetermined relationship occurs between the output of said staircase generator and the output of said voltage ramp generator and for producing an output signal therefrom when a said predetermined relationship occurs;

(h) third means interconnecting said staircase ygenerator and said voltage ramp generator `with said beam scanning control means;

(i) beam generator control means responsive to said Ibeam scanning control means for producing an electrical signal output adapted to actuate a beam source;

(j) beam deecting control means responsive to said beam scanning control means for moving a said beam through a predetermined scan sequence; and

(k) beam programming means responsive to said beam scanning control means for controlling the actuating interval of said beam generator control means and for actuating said beam deflecting control means to return a said `beam to a starting position.

4. An electrical control system for synchronizing the scanning movements of a high energy beam on the peripheral surfaces of a rotating -body so that said beam mpinges on a particular point of said body during a predetermined arcuate displacement of said body, said body having a reference means associated therewith for providing reference information concerning the position of at least one prechosen point located on peripherla surfaces of a said body, said system comprising (a) a first signal generating means for producing signals in response to such reference information indicating revolutions of a said body;

(b) a second signal generating .means for producing signals in response to such reference information indicating arcuate displacement of said one point during each revolution;

(c) beam scanning control means for detecting when a predetermined relationship occurs between the output of said first signal generating means and the output of said second signal generating means and for producing an output signal therefrom when a said predetermined relationship occurs;

(d) means interconnecting each of said first signal generating means and said v,second signal generating means with said beam scanning control means;

(e) beam generator control means responsive to said beam scanning control means for producing an electrical signal output adapted to actuate a beam source;

(f) a first beam defiecting control means responsive to said beam scanning control means for moving a said -beam through a predetermined scan -sequence in a first direction;

(g) a second beam defiecting control means responsive to said beam scanning control means for moving said beam through a predetermined displacement in a direction other t-h'an said first direction; and

(h) beam programming means responsive to said beam scanning control means for controlling the actuating interval of said beam generator control means and for actuating said beam deflecting control means to return a said beam to a starting position.

5. An electrical control system of claim 1 wherein the beam scanning control means comprises (a) a unijunction transistor having an emitter, a first base and a second base;

(b) means adapted for connecting a lfirst electrical signal to the emitter;

(c) means adapted for connecting a second electrical signal to the first base;

(d) means for connecting the second 4base to a reference potential, the electrical signal being applied to the emitter and to thejfirst base and being of a predetermined relationship as determined `by the conducting characteristics t,of the unijunction transistor, such that said transistor conducts to produce an output signal between at least one base and the reference potential.

6. A method for synchronizing for a predetermined period of time scanning movements of a high energy beam with a predetermined' point on the surface of a rotating body, wherein the source of said high energy beam is maintained at a fixed distance from the surface of said rotating body, said method comprising the steps of (a) generating signals in response to rotational move- 5 ments of said body to indicate the angular position of a said predetermined point on the surface of a said rotating body;

(b) transmitting said signals to control means for establishing the occurrence of la said predetermined point on said body reaching a predetermined position with respect to said fixed beam source; and

(c) synchronizing the scanning rate of said beam with the angular velocity of' a `said predetermined point while simultaneously maintaining the intensity of such beam at a predetermined level for a predetermined interval of time.

7. An electrical control system of claim 1 wherein the beam scanning control means includes a sample and hold circuit, said sample and hold circuit comprising (a) a first field effect transistor having a source, a drain and a gate;

(b) input means adapted for applying 'an input signal to said source;

(c) a capacitor having a first and second terminal;

(d) a second field effect transistor having a source, a

drain and a gate;

(e) said capacitor having said first terminal connected to said drain of said first field effect transistor and to said gate of said second field effect transistor, and having said second terminal adapted for connection to a fixed referencepotential;

(f) means connected to said drain of said second field effect transistor for connection to a source of negative potential;

(g) means connected to said source of said second field effect transistor, including resistance means, being adapted for connection to a source of positive potential;

(h) output means connected to said source of said second 4field effect transistor; and

(i) means connected to said gate of said first field effect transistor to adjust the impedance between said source and said drain of said first field effect transistor for adjusting the charge on said capacitor to said input signal and for isolating said charge, whereby said impedance may be lowered to afford said capacitor to charge to a charge level of an input signal and said impedance may Ibe raised and held to be reflected between said output means and a reference potential.

No references cited.

ROBERT L. GRIFFIN, Primary Examiner. 55 R. K. ECKERT, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE 0F CORRECTIGN Patent No. 3,398,237 August 20, 1968 Richard L. Paidosh It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 4, line 13, "deflecon" should read deflection Column 5, line 32, "sentatves" should read sentative Column 6, line 50, "18" should read 128 line 60, "ressitor" should read resistor Column 7, line 3, after "192" cancel The transistor 156 has a base 194, a collec" and insert so as to apply the voltage appearing across Column 13, line 3, "peripherla" should read peripheral Signed and sealed this 25th day of August 1970.

(SEAL) Attest:

Edward M. Fletcher, Ir.

Attesting Officer Commissioner of Patents 

1. AN ELECTRICAL CONTROL SYSTEM FOR SYNCHRONIZING THE SCANNING MOVEMENTS OF A HIGH ENERGY BEAM ON THE PERIPHERAL SURFACES OF A ROTATING BODY SO THAT SAID BEAM IMPINGES ON A PARTICULAR POINT OF SAID BODY DURING A PREDETERMINED ARCUATE DISPLACEMENT OF SAID BODY, SAID BODY HAVING REFERENCE MEANS ASSOCIATED THEREWITH FOR PROVIDING REFERENCE MEANS ASSOCIATED THEREWITH FOR OF AT LEAST ONE PRECHOSEN POINT LOCATED ON PERIPHERAL SURFACES OF A SAID BODY, SAID SYSTEM COMPRISING (A) A FIRST SIGNAL GENERATING MEANS FOR PRODUCING SIGNALS IN RESPONSE TO SUCH REFERENCE INFORMATION INDICATING REVOLUTIONS OF A SAID BODY; (B) A SECOND SIGNAL GENERATING MEANS FOR PRODUCING SIGNS IN RESPONSE TO SUCH REFERENCE INFORMATION INDICATING ARCUATE DISPLCEMENT OF SAID ONE POINT DURING EACH REVOLUTION; (C) BEAM SCANNING CONTROL MEANS FOR DETECTING WHEN A PREDETERMINED RELATIONSHIP OCCURS BETWEEN THE OUTPUT OF SAID FIRST SIGNAL GENERATING MEANS AND THE OUTPUT OF SAID SECOND SIGNAL GENERATING MEANS AND FOR PRODUCING AN OUTPUT SIGNAL THEREFROM WHEN A SAID PREDETERMINED RELATIONSHIP OCCURS; (D) MEANS INTERCONNECTING EACH OF SAID FIRST SIGNAL GENERATING MEANS AND SAID SECOND SIGNAL GENERATING MEANS WITH SAID BEAM SCANNING CONTROL MEANS; (E) BEAM GENERATOR CONTROL MEANS RESPONSIVE TO SAID BEAM SCANNING CONTROL MEANS FOR PRODUCING AN ELECTRICAL SIGNAL OUTPUT ADAPTED TO ACTUATE A BEAM SOURCE; (F) BEAM DEFLECTING CONTROL MEANS RESPONSIVE TO SAID BEAM SCANNING CONTROL MEANS FOR MOVING A SAID BEAM THROUGHT A PREDETERMINED SCAN SEQUENCE; AND (G) BEAM PROGRAMMING MEANS RESPONSIVE TO SAID BEAM SCANNING CONTROL MEANS FOR CONTROLLING THE ACTUATING INTERVAL OF SAID BEAM GENERATOR CONTROL MEANS AND FOR ACTUATING SAID BEAM DEFLECTING CONTROL MEANS TO RETURN A SAID BEAM TO A STRTING POSITION.
 6. A METHOD FOR SYNCHORIZING FOR A PREDETERMINED PERIOD OF TIME SCANNING MOVEMENT OF A HIGH ENERGY BEAM WITH A PREDETERMINE POINT ON THE SURFACE OF A ROTATING BODY, WHEREIN THE SOURCE OF SAID HIGH ENERGY BEAM IS MAINTAINED AT A FIXED DISTANCE FROM THE SURFACE OF SAID ROTATING BODY, SAID METHOD COMPRISING THE STEPS OF (A) GENERATING SIGNALS IN RESPONSE TO ROTATIONAL MOVEMENT OF SAID BODY TO INDICATE THE ANGULAR POSITION OF A SAID PREDETERMINED POINT ON THE SURFACE OF A SAID ROTATING BODY; (B) TRANSMITTING SAID SIGNALS TO CONTROL MEANS FOR ESTABLISHING THE OCCURRENCE OF A SAID PREDETERMINED POINT ON SAID BODY REACHING A PREDETERMINED POSITION WITH RESPECT TO SAID FIXED BEAM SOURCE; AND (C) SYNCHRONIZING THE SCANNING RATE OF SAID BEAM WITH THE ANGULAR VELOCITY OF A SAID PREDETERMINED POINT WHILE SIMULTANEOUSLY MAINTAINING THE INTENSITY OF SUCH BEAM AT A PREDETERMINED LEVEL FOR A PREDETERMINED INTERVAL OF TIME. 